Revive this file -- to try out an experimental

version of AC_FUNC_STRERROR_R that may work even on BeOS, a system
for which strerror does return char*, but which lacks a conveniently
accessible declaration of the function.

m4/strerror_r.m4

@@ -0,0 +1,44 @@
+#serial 1000
+# Experimental replacement for the function in the latest CVS autoconf.
+# Use with the error.c file in ../lib.
+
+undefine([AC_FUNC_STRERROR_R])
+
+# AC_FUNC_STRERROR_R
+# ------------------
+AC_DEFUN([AC_FUNC_STRERROR_R],
+[# Check strerror_r
+AC_CHECK_FUNCS([strerror_r])
+if test $ac_cv_func_strerror_r = yes; then
+  AC_CHECK_HEADERS(string.h)
+  AC_CHECK_DECLS([strerror_r])
+  AC_CACHE_CHECK([for working strerror_r],
+                 ac_cv_func_strerror_r_works,
+   [
+    AC_TRY_COMPILE(
+     [
+#       include <stdio.h>
+#       if HAVE_STRING_H
+#        include <string.h>
+#       endif
+#ifndef HAVE_DECL_STRERROR_R
+"this configure-time declaration test was not run"
+#endif
+#if !HAVE_DECL_STRERROR_R
+char *strerror_r ();
+#endif
+     ],
+     [
+       char buf;
+       char x = *strerror_r (0, &buf, sizeof buf);
+     ],
+     ac_cv_func_strerror_r_works=yes,
+     ac_cv_func_strerror_r_works=no
+    )
+    if test $ac_cv_func_strerror_r_works = yes; then
+      AC_DEFINE_UNQUOTED(HAVE_WORKING_STRERROR_R, 1,
+        [Define to 1 if `strerror_r' returns a string.])
+    fi
+  ])
+fi
+])# AC_FUNC_STRERROR_R